Field of the Invention
The present invention relates to a semiconductor package, and in particular, to a solder resist layer design of a flip chip package.
Description of the Related Art
For the conventional flip chip package, it is well known that the underfill protects the conductive bumps by considerably reducing the stress to the conductive bumps. However, the underfill itself is subject to shear or peeling stress and consequently, may induce failure modes. For instance, an imperfect underfill with voids or microcracks will produce cracks or delamination under temperature cycling conditions.
Delamination at bimaterial interfaces such as the underfill and conductive traces, driven by coefficient of thermal expansion (CTE) mismatching between organic underfills and inorganic conductive traces, is one of failure modes. Once the underfill delamination, occurs, failure usually results from conductive bump fatigue cracks because of the loss of the underfill protection and stress concentration arising from the underfill delamination.
Thus, a novel flip chip package without the underfill delamination is desirable.